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carborundrum grinding disks

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jon hill 331/08/2020 22:41:53
166 forum posts
40 photos

I have an old bench tool grinder, 400w, 3000rpm, 150mm which is approximatly 40yrs old. However to the best of my knowledge the carborundrum disks have never been changed or ping tested since fitted. They have been regularly surface dressed and have not been abused, ie edges are reasonable straight, no noticable uneven wear or dents.

Should I be worried, or take further safety measures?

clogs01/09/2020 06:56:03
630 forum posts
12 photos

Dear JON,

when did it last get used...?

provided it hasn't been dropped on the floor or got wet I'd say u'd be just fine...

best bet, stand to one side and turn it on.....IT IS BOLTED DOWN>....?

if it vibrates badly change the stones.....

is it noisy, bearings.....? often the grease gets hard.....

try it and lets un know.....

unless u pay loads, modern grinders are rubbish...yes they do the job ....JUST...

Nicholas Farr01/09/2020 08:27:04
avatar
3988 forum posts
1799 photos

Hi Jon, the best advice I can give you is to consult the manufacturers guidance. However the the lifespan of grinding wheels is mostly down to the bonding of the grinding particles, vitrified bonded wheels usually last much longer then resin bonded wheels. If you have doubts at all about the safety of your wheels, it is best to replace them, especially given the age of them. As clogs has said, you should not stand in front of any grinding wheel during start up, as this is the time when the wheels are at their most stressful stage. Below is info on wheel classification.

grinding wheels 002.jpg

Regards Nick.

jon hill 301/09/2020 10:37:47
166 forum posts
40 photos

img_4925.jpgJust to add some further detail its a kef motor grinder. Its had faily constant use, bolted down to a steel bench and has no vibration issues except on startup and de-celeration and even then its not that noticeable.

 

The course and fine disks fitted are a blue composite that looks similar to carborundrum.

I will add a picture later.

Edited By jon hill 3 on 01/09/2020 10:47:22

jon hill 301/09/2020 10:49:45
166 forum posts
40 photos

img_4924.jpgimg_4922.jpg

jon hill 301/09/2020 10:51:12
166 forum posts
40 photos

Pics of the coarse and fine disks for identification if anyone knows what type they are?

Nicholas Farr01/09/2020 11:03:58
avatar
3988 forum posts
1799 photos

Hi Jon, they look like vitrified wheels to me, but one way to find out is to take them off and see if there is a classification code on the blotting paper. The top picture looks as if the blotting paper is actually degrading, it is important that these should be sound. Mounting the Wheels info below.Abrasive Wheel Mounting.jpg

Regards Nick.

Edited By Nicholas Farr on 01/09/2020 11:06:59

jon hill 301/09/2020 11:21:31
166 forum posts
40 photos

Hi Nick

Thanks for the feedback.

Just a few more questions, should the paper be bonded to the disk and does this dampen vibration and normal stress to the wheel?

Nicholas Farr01/09/2020 11:44:18
avatar
3988 forum posts
1799 photos

Hi Jon, the papers each side don't have to be bonded, but are normally stuck with relatively low strength adhesive as it makes it easier to mount the wheel as they don't have a small hole in the middle that will fit the shaft, but they do need to be a little compressive, like blotting paper is, as they act as a soft buffer between the wheel and the steel flanges and take up any small irregularities on the surface of the wheel side and of course gives the grip needed between the flanges and the wheel. Do not mount a wheel without one on each side. The scan below may be helpful to you.

examin.jpg

Regards Nick.

P.S. I believe many people cut their blotters from cereal packets.

Edited By Nicholas Farr on 01/09/2020 12:15:16

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